Cyclone mills



Jan. 17, 1956 E. MARE CYCLONE MILLS Filed Oct. 8, 1952 United StatesPatent CYCLONE MILLS Ernest Mare, Johannesburg, Transvaal, Union ofSouth Africa Application October 8, 1952, Serial N 313,671

10 Claims. (Cl. 241-56) and relates particularly to the type of millwhich comprises;

a chamber housing a rotor which latter acts to disintegrate 2,731,209Patented Jan.v 17, 1956 which may be of any suitable shape, and therotor 3 is fitted with projecting members of different types depend ingon the purpose for which the mill is to be used.

For example, in the milling of asbestos cobs, the rotor 3 is fitted withreplaceable fins 23 and the material is fed into the conical chamber 1through inlet 2 and directed onto the rotor 3 which projects itoutwardly so that it impacts the liners 22 of the wall 6 causing aseparation of the rock and fibre. The air-stream from the fan 16 passesthrough the passageways 9 and radially over the base 4 of the rotor 3 asindicated by the arrows, scavengingthe the material fed onto the rotorby projecting it outwardly against the walls of the chamber.

In this type of mill the light or fine material is entrained in an airstream to be discharged from the mill and the control of the degree ofmilling and/or separation is very largely dependent on the strength anddirection of the air stream. It is the object of this invention toprovide a mill in which the air stream through the mill may be moreefiectively utilized for the separation of the material to be treatedand also to provide means for the eflicient breaking up and/ or blendingof the material.

According to this invention there is provided a mill comprising achamber provided with a discharge opening and housing a rotor having anoutwardly flanged base forming the floor of the chamber, inlet airpassageways to the chamber through the lower part of the rotor, meansfor directing the inlet air radially over the flanged base, and a fan orthe like for discharging a stream of air upwardly through said inlet airpassageways.

This invention is illustrated in the accompanying drawings in which:

Fig. 1 is a sectional side elevation of the centrifugal mill;

Fig. 2 is a view similar to Fig. l but showing the top structure only ofa modified type of mill, and

Fig. 3 is a view similar to Fig. 2 showing a further modified form ofthe invention.

As shown in Fig. 1 there is provided a truncated conical chamber 1 witha discharge opening 2 at its apex. Inside the chamber 1 is fittedcentrally a conical rotor 3 with its axis vertical and having anoutwardly flanged base 4 with a clearance space 5 between the walls 6of-the chamber 1 and the periphery of the flanged base 4. The bottom ofthe rotor 3 is mounted on a boss 7 secured to the upper end of avertical shaft 8. Air passageways 9 are provided curving outwardly belowthe coned portion of the rotor 3 to direct the air stream radially overthe top of the flanged base 4 which forms the floor 10 of the chamber 1.

The walls 6 of the conical chamber 1 are mounted on suitable stanchions11 to which are secured the bearings 12, 13 for the shaft 8 carrying therotor 3, a pulley 14 being secured to the shaft 8 between the bearings12, 13. Below the floor 10 of the conical chamber 1 is a second chamber15 conveniently closed by the upper bearing 13 of the rotor shaft 8. Afan 16 is secured to the lower end of the rotor shaft 8 and is enclosedin a housing 17 attached to the stanchions 11 and connected by asuitable air duct 18 to said second chamber 15. The fan intake 24 isfitted with a sliding cover 19 or the like, to control the flow of airthrough the same.

The conical chamber 1 has a feed chute or pipe 20 directed towards theapex 21 of the rotor 3. The inner Walls 6 of the chamber are fitted withreplaceable liners 22 separated fibre and lighter rock particles fromthe floor 10 of the chamber 1' and carrying them upwardly through thedischarge duct 2 whence they are led to a decompression chamberandcyclone. separator in the normal way. The air may be discharged toatmosphere from the cyclone or alternatively led back to the fan intake24 in a closed circuit thus obviating the necessity for an additionalfan.

The particles which are too heavy to be entrained in the air stream aresubjected to repeated attrition or impact in the mill until they haveattained the requisite degree of fineness, the size of theparticles-finally discharged being, of course, dependent on the strengthof the air stream which can be controlled by the cover 19 of fan inlet24. A certain amount of the air will flow through the clearance space 5and assist in preventing material falling below the rotor 3. a

.The fan 16 may be connected to the rotor shaft 8 through suitablegearing so that its speed relative-to the rotor 3 may be varied. This isparticularly desirable, for instance, in one modification of thisinvention, as shown in Fig. 3, in which balls are inserted in thechamber 1 to assist or effect the milling operation. In this case therotor 3 will normally be rotated at a slower speed than the fan 16 andthe flanged rotor base 4 and adjacent surfaces are curved to form anannular dished floor 25 for the chamber which assists in confining themovements of the balls 28. For normal operations however, and as shownin Fig. l the base 4 of the rotor 3 is flat and has mounted thereon anumber of radially positioned beater bars 29, and fan 16 and rotor 3 aremounted on the same shaft 8.

The mill according to this invention is also applicable for use in theblending or mixing of materials particularly those which are in a finelydivided and/or friable form, such as pigments for paints and milledasbestos fibres. In this case the inlet 20 is preferably closed and thematerial fed in through the fan inlet 24. The incoming material isinitially broken up and mixed in its passage through the fan 16, duct 18and chamber 15 and the process completed by the rotor 3 in thechamber 1. The mixing of the material-may be further assisted by fittingthe rotor with outwardly and radially projecting arms 26, as in Fig. 2,which rotate between corresponding arms 27 projecting inwardly from thewalls 2.

The mill may also be used for treatment of relatively soft materialssuch as the dehulling of tung nuts. in this case to prevent completebreakdown of the nuts it is generally necessary to remove the upper partof the rotor 3 and the beater bars 29 and for this reason, and also forreplacement, they are made easily detachable.

In all cases the flow of air upwardly through the lower part of therotor and outwardly over the flanged base of the same acts to ensureproper scavenging and control of the dimensions and/or weight of theproduct discharged through the outlet 2.

What I claim as new and desire to secure by Letters Patent is:

l. A cyclone mill comprising a housing having walls forming a chamber, arotor having a conical upper surface and a flange-shaped base bothrotatably supported in said chamber, said rotor having fins projectingradially from said conical surface, said base having beater bars 3 onits upper side forming grooves therebetween and extending radially fromadjacent the bottom of said conical surface to the periphery of saidbase, said base also having passageways extending through it from bottomto top,

said passageways including means for forcing air upwardly through them;the peripheral edge of said base and the adjacent portion of saidchamber walls being inclined upwardly and outwardly relative to thebottom of said base to form an annular space of matching inclination,

and means for forcing a stream of air upwardly through said annularspace and for assisting flow through said passageways.

2'. A cyclone mill comprising a housing having first walls forming achamber, a rotor having a conical upper surface and a flange-shaped baseboth rotatably supported in said chamber, said rotor" having finsprojecting radiallyfrom said conicalsurface, the peripheral edge ofsaidbase being spaced from said chamber walls, and a 'fan for forcingair upwardly through the space between said base and said walls.

'3'. A cyclone mill as claimed in claim 2 in which said housing includesan inlet passage directed toward the center of-said rotor.

4'. A cyclone mill as claimed in claim 2- in which said chamber includesan inlet aperturepositioned above and 7. A cyclone mill as claimed inclaim 2 in which said housing has second walls forming a fancasing, saidfan being located in said casing, said casing being positioned belowsaid rotor and having a discharge connection to a position adjacent thebottom of said base.

8. A cyclone mill comprising a housing having walls forming a chamber, arotor having a conical upper surface and a flange-shaped base bothrotatably supported in said chamber, said rotor having fins projectingradially from said conical surface, the peripheral edge of said base andthe adjacent portion of said chamber walls being inclined upwardly andoutwardly relative to the bottom of said base. to form anannular'spaceofimatchingrincli-nation, means for forcing a stream of air upwardlythrough said annular space, and means for directing a flow of airradially outwardly across the top of said base.

9. A cyclone mill as claimed in claim 8 in which said rotor has at leastone arm projecting radially outwardly from said conical surface and inwhich said chamber walls have adjacent said conical surfac'cat least onearm project-- ing radially inwardly, said" arms having an overlappingrelation between them.

10; A cyclone mill as claimed in claim 8 in which said base has a dishedupper surface, and balls distributed in said dished uppersmface;

References Cited'inthe file of this patent UNITED STATES PATENTS2,092,307 Gaft'ney' Sept. 7',v 1937 FOREIGN PATENTS 352,443 GreatBritain"Minn-" Aug. 6,. 1.931

